Conventionally, there has been known a vehicle door frame that includes an upper sash and a hollow side sash which abut on and are joined to each other in the corner of a vehicle door (for example, Japanese Patent Application Laid-open Publication No. 6-286463 and No. 2014-151659).
In such a vehicle door frame, for example, air may enter the internal space of the side sash from a joint between the upper sash and the side sash during traveling of a vehicle, generating wind noise.
An object of the present invention is to provide a vehicle door frame having a novel structure which can prevent occurrence of wind noise.